93 lines
2.7 KiB
Python
93 lines
2.7 KiB
Python
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import json
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import secrets
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import logging
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from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
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from cryptography.hazmat.backends import default_backend
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logger = logging.getLogger(__name__)
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def generate_imsi(mcc: str, mnc: str) -> str:
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"""Generate a random 15-digit IMSI: MCC + MNC + MSIN.
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IMSI is always 15 digits. MCC is 3 digits; MNC is 2 or 3 digits, so the
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MSIN fills the remaining 9 or 10 digits.
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"""
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msin_len = 15 - len(mcc) - len(mnc)
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if msin_len <= 0:
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raise ValueError(f"MCC/MNC too long for a 15-digit IMSI: {mcc!r}/{mnc!r}")
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msin = str(secrets.randbelow(10**msin_len)).zfill(msin_len)
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imsi = mcc + mnc + msin
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assert len(imsi) == 15, f"IMSI length error: {imsi!r}"
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return imsi
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def generate_ki() -> bytes:
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"""Generate a 16-byte cryptographically random authentication key."""
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return secrets.token_bytes(16)
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def luhn_checksum(number: str) -> int:
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"""Compute the Luhn check digit for a string of digits."""
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digits = [int(d) for d in number]
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odd_digits = digits[-1::-2]
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even_digits = digits[-2::-2]
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total = sum(odd_digits)
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for d in even_digits:
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total += sum(divmod(d * 2, 10))
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return (10 - (total % 10)) % 10
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def generate_iccid() -> str:
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"""Generate a 19-digit ICCID with a valid Luhn check digit.
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Format: 8910 (telecom prefix) + 10 random digits + 5 more + Luhn digit = 19 total.
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"""
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prefix = "8910"
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body = prefix + str(secrets.randbelow(10**14)).zfill(14) # 18 digits
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check = luhn_checksum(body)
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return body + str(check)
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def derive_opc(ki: bytes, op: bytes) -> bytes:
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"""Derive OPc from Ki and OP using the Milenage algorithm.
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OPc = AES_Ki(OP) XOR OP
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"""
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cipher = Cipher(algorithms.AES(ki), modes.ECB(), backend=default_backend())
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enc = cipher.encryptor()
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encrypted_op = enc.update(op) + enc.finalize()
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return bytes(a ^ b for a, b in zip(encrypted_op, op))
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def create_esim_profile(
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imsi: str,
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ki: bytes,
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opc: bytes,
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iccid: str,
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profile_name: str,
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carrier_name: str,
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) -> bytes:
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"""Create an eSIM profile.
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Phase 1: returns a JSON-encoded mock profile suitable for end-to-end
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testing. Phase 2 (Unit 06 upgrade): replace with real pySim SGP.22
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profile generation.
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"""
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ki_hex = ki.hex() if isinstance(ki, bytes) else ki
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opc_hex = opc.hex() if isinstance(opc, bytes) else opc
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profile = {
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"version": "1.0",
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"type": "mock",
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"iccid": iccid,
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"imsi": imsi,
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"ki": ki_hex,
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"opc": opc_hex,
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"profile_name": profile_name,
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"carrier_name": carrier_name,
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}
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logger.debug(f"Created mock eSIM profile for IMSI {imsi}")
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return json.dumps(profile, indent=2).encode("utf-8")
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